Vacuum lift device



Feb. 25, 1941. w. L. NELSON VACUUM LIFT DEVICE Filed Oct. 20, 1939 2Sheets-Sheet 1 .N S. NN 8 WN. Q.,

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VACUUM LIFT DEVICE Filed oct. 2o. 19:59 2 shuts-sheet 2 Nm om am mvINVENTOR W/LL /M L. NELSON BY ATTORNEY Patented Feb. 25, 1941 UNITEDSTATES VACUUM LIFT DEVICE William L. Nelson, South Holland, Ill.,assignor to United States Gypsum Company, Chicago, Ill., a corporationof Illinois Application October 20, 1939, Serial No. 300,327 s claims.(c1. zei-cm' This invention relates to lift devices, and has referencemore particularly to vacuum lift devices suitable for lifting andtransporting sheets of flexible material, such as asbestos-cement sheetshingle stock.

In the manufacture of asbestos-cement shingles, siding and industrialsheet material of all kinds, it is customary to manufacture large sheetsof the asbestos-cement stock material.

After forming the sheets, they are lifted from the forming conveyor byavacuum lift box and deposited on. a conveyor which carries the sheetthrough the platens of a hydraulic press. A wood grain imprint ispressed onto the top surface of the sheet by the press and the conveyorthen transfers the sheet to the delivery side of the press. Here anothervacuum lift box engages the grained upper surface of the -sheet andtransfers the sheet to a skid to permit the cement to set over a periodof several hours. In the vacuum lift boxes previously used, the lowersurface'of the box has been covered with porous screen wire backed up bysuitable frame work. It has always been thought that the vacuum must beapplied to the entire face of the sheet by the use of the screen wire.However, it has been found. that the press of the screen on the plasticembossed surface of the sheet, leaves the imprint of the wire meshes onthe protruding 3 embossed ridges of the surface of the sheet.

These wire mesh imprints on the sheet are objectionable and decrease thesalability of the resulting shingles.

An object of the invention, therefore, is to` 35 provide a vacuum box inwhich the objectionable screen wire is eliminated and a flat sheet withperipheral vacuum applying holes is used.

Another object of the invention is to decrease the weight and improvethe lifting powerof a 0 vacuum lift box.

A further object of the invention is to produce an embossed sheetofasbestos cement which is free of screen wire imprints; also to improvevacuum lift boxes and asbestos cement sheet 45 products in otherrespects hereinafter specified and claimed.

Reference is to be had to the accompanying drawings forming a part ofthis specification, in which Fig. l is a plan view of the vacuum liftbox,

Fig. 2 is a sectional elevation through the box taken on line 2-2 ofFig. 1,

Fig. 3 is a bottom view of the box,

Fig. 4 is a sectional elevation on an enlarged 55 scale taken on line4-4 of Fig. 1, and

Fig..5 is a diagrammatic view showing the piping and other apparatusassociated with thebox.

Referring to the drawings by numerals, the vacuum box III is connectedby a pipe II to a vacuum tank I2 having av drain valve I3. A three wayvalve I4 is provided on the pipe II to apply the vacuum for liftinga.sheet I5, said valve I4 also being arranged to release the vacuumtodeposit the ysheet at a desired point. A pipe I6 connects the tank I2 toa vacuum 10 pump Il,

'I'he box I0 comprises transverse channel ,beams or frames I8, I9 and 20secured to longitudinal channel beams or frames 2l by angle r cups z2and bolts 2s. u-bars 24, preferably four 1 in number, are provided withflattened ends which are secured to the frame members I8, 20 and 2I bybolts 26. A hoisting chain 21 is secured at one end to each of U-bars24, the opposite ends of said chains being connected to a 20 ring 28. Apneumatic or other type of hoist not shown, may be attached to the ring28 to lift the vapparatus carrying a sheet of material. End channelframes 29 are secured to the ends of channels 2| by angle clips 30.

Metal bars 32 extend around the periphery of the box below outstandinglower flanges 33 formed on the channel frames 2| and 29, being securedthereto by bolts 34. A longitudinal groove or air passage 35 extendsalong the bottom face of each bar 32 and branch pipes 36 are connectedat intervals to the inside of each bar 32. The branch pipes 36 join inan air manifold 31 which is joined by flexible hose 38 to the vacuumtank I2. A metal sheet 39 is secured about its pe- 3* riphery by screws40 and bolts 34 to the channel anges 3 3. Screws 4I secure the sheet 39to the channels I8, I9 and 20 intermediate the edges of said sheet 39. Aseries of air holes 43`are formed around the periphery of sheet 39, saidholes registering with the grooves 35. In order to seal the box aroundthe periphery, with the sheet of asbestos-cement shingle material I5, Iattach a thick strip of medium soft rubber 45 to channels 2| and bars 32by a metal strip 46 and screws 41 and 48 respectively. A strip of hardrubber 49 is interposed between the rubber strip 45 and metal strip 49in order to back up and stiifen the rubber strip 45. The lower edge ofrubber strip 45 is provided with a bevel 50 50 which forms a sealingedge 5I on the bottom of said strip 45. I prefer to make all metalparts, where possible, of Dow metal, a. magnesium base alloy, because ofits lightness and strength. Other light weight metals may of course beused.

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It will be seen that as Ithe sheet 39 is imper- -forate or air-tightinside the peripheral air holes 43. no defacing marks will be producedon the upper surface of the sheet I5, as were produced by the older typeof lift box in which screen wire was used on the lower surface of thebox. thermore, the vacuum is evenly applied over the face of thesheet I5when the air holes 43I are arranged only around the periphery of thesheet 39, contrary to the accepted belief that air holes have to belocated throughout the area of` the sheet.

I would statev in conclusion that, while the illustrated exampleconstitutes a practical embodiment o1' my invention, I do not wish tolimit myself precisely to these details, since manifestly that same maybe considerably varied without departing from the spirit of theinvention as dened inthe appended claims.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

1. In a vacuum lift device, a substantially imperforate rigidly heldsheet of material, sealing means around the periphery of said sheet forforming a substantially air-tight seal with a supported sheet of exiblematerial, said first sheet being provided with a series oi" peripheralair holes adjacent said sealing means, and means i'or applying vacuumthrough said holes to draw said iiexible sheet against said nrst sheetand said sealing means. Fur- 2. In a vacuum lift device, a supportingframe, a. rigid bar member extending about the periphery of said frame,a substantially imperforate sheet rigidly supportedby said frame and barmember, said bar member having a longitudinal vslot formed in the bottomsurface thereof, air

holes around the periphery of said sheet and communicating with saidslot, sealing vmeans around theperiphery of said frame', and means forappyling vacuum to said slotted bar and sheet so as to draw a flexiblesheet oimaterial against said sealing vmeans and said rst sheet.

s. In a vacuum nft device, a sheet of rigidlyy held material having airholes only around the periphery thereof, means for attaching said sheetto a hoist, sealing means adjacent the pe-l -riphery of said sheet, andmeans for applying a vacuum to said holes so as to draw a flexiblesheet. of material against saidfirst sheet and said sealing means.

` WILLIAM L. NELSON:

